Calcium chloride exists as dihydrate (CaCl2x2h20). it has 2 valence. according to the definition of valence: "valence, combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound. Atoms are called monovalent, divalent, trivalent, or tetravalent, according to whether they form one, two, three, or four bonds." this means that the valence of calcium alone (ca2+) is 2 and chloride (cl-) alone is 1. then why the valence of CaCl2 is 2? hope for replies!!! thanks!